Disable macOS 15 features in QCocoaCursor

Bypasses an undefined reference to ___isPlatformVersionAtLeast
for the @available(macOS 15, *) check.

Can be dropped once OSX_MIN_VERSION is updated to 15.0+.

The disabled code was introduced in 4aeb27fbacfade7106b19c460deb5414143a5e53.
The referenced QTBUG-126240, in turn, refers to the NSCursor API for window
resize cursors.


--- a/qtbase/src/plugins/platforms/cocoa/qcocoacursor.mm
+++ b/qtbase/src/plugins/platforms/cocoa/qcocoacursor.mm
@@ -138,7 +138,7 @@ NSCursor *QCocoaCursor::convertCursor(QCursor *cursor)
     case Qt::SizeHorCursor:
     case Qt::SizeBDiagCursor:
     case Qt::SizeFDiagCursor: {
-#if QT_MACOS_PLATFORM_SDK_EQUAL_OR_ABOVE(150000)
+#if 0
         if (@available(macOS 15, *)) {
             auto position = [newShape]{
                 switch (newShape) {